After trying to catch bullets in lined up 2 liter bottles of water with no luck,(in retrospect: the angle of impact and plastic bottles may have been the cause of the severe deformation) I decided to resort to a shredded tire medium.
Enjoy:
Home Depot
---------------------------------
(4X) 048834019140 VIG RUBR RED 35.88
(2X) 026703055550 HOMER BUCKET 9.96
(1X) 039645692226 10" CONCRTUBE 8.79
Total: 54.63
Pictures of construction & Testing to follow. It's possible that when filled with water and set at a 45 degree angle off the ground, the angle of entry will make the rubber medium unnecessary. If that's the case, the rubber medium becomes the "indoor target practice/lead dust free bullet trap" version.